KAWA MULTIMEDIA PUBLICATIONS
The Cabora Bassa Dam in Mozambique
This dam has been built at the downstream end of the Quebrabasa Gorge, one of many that the Zambezi has carved on its way to the sea. It is an ideal site for a dam. The gorge sides are of hard, resistant rock which is well able to support the side foundations of the dam. The gorge is narrow and thus easily blocked.
The dam was started in 1969 and the first phase was finished six years later in March 1975. It is 160 metres high and 300 metres long at the top and is a typical example of an arch dam: a dam which does not depend on huge bulk for its strength. The stresses and strains are contained by the design: a curve which, facing upstream, deflects the force and weight of the water to either side of the dam where its foundations are firmly embedded into the gorge side.
The man-made lake behind it took several years to fill, but now stretches over 300 kilometres upstream as far as the Zambian border. The power it produces is colossal: more than 2000 megawatts from its five 408 megawatt generators. A north bank power station is now ordered and will be ready by 1987. It will produce a further 2000 megawatts.
Although South Africa financed the dam, Cabora Bassa is at present (1983) 80% owned by Portugal and only 20% by Mozambique. At present (1983) South Africa takes most of the power produced by way of twin 1900 kilometres long transmission lines to the Apollo converting station near Pretoria.
Since announcing the north bank development, Mozambique has decided to reduce supplies to South Africa. A 2000 kilometre power line has been extended through Mocuba in the north as far as Nampula. It is now ready to power a new aluminium industry, iron and steel near Moatize, textile production, cashew nut factories, and the homes of Mozambique people themselves.
The dam has also brought agricultural benefits. Most of the whole region's rainfall comes between November and-April. The Zambezi flooded uncontrollably. During the other months there was often only a trickle of water along parts of its course. Soon, the Mpenda Uncua scheme which is 40 kilometres below Cabora Bassa and two other dams further downstream will ensure more power, flood control and reliable navigation facilities as far upstream as Tete.
Agricultural losses from flooding have been reduced and irrigation supplies new cotton, sugar and rice developments. Piped water will supply cattle and afforestation projects near Malawi,
Minerals should soon be exploited. The coal mines at Moatize can be expanded, there are iron ore reserves capable of yielding 1 million tonnes a year and perhaps the bauxite on Mount Mianje in Malawi can be exploited. The 170 square kilometres man-made lake will provide the basis for a fishing industry which could supply the region with its needs for protein.
No project of this size is without its problems. The land to be flooded by the lake had 25000 people living on it. They had to be resettled and this has been done around Moatize and Zobue, on land which will come under irrigation.
Cabora Bassa was a political dam, built by the South Africans and Portuguese to perpetuate their nold on the region. The Cunene Dam and Oxbow have similar aims. The money that migrant workers send home from South Africa, forming a major part of the income for Mozambique and Malawi, also had this aim. South Africa hopes that by weaving a vast interdependent economic web amongst her neighbours they will hesitate to shatter its stability and obvious benefits, by trying to overthrow her political system. Only time will produce the answer.
The dam was started in 1969 and the first phase was finished six years later in March 1975. It is 160 metres high and 300 metres long at the top and is a typical example of an arch dam: a dam which does not depend on huge bulk for its strength. The stresses and strains are contained by the design: a curve which, facing upstream, deflects the force and weight of the water to either side of the dam where its foundations are firmly embedded into the gorge side.
The man-made lake behind it took several years to fill, but now stretches over 300 kilometres upstream as far as the Zambian border. The power it produces is colossal: more than 2000 megawatts from its five 408 megawatt generators. A north bank power station is now ordered and will be ready by 1987. It will produce a further 2000 megawatts.
Although South Africa financed the dam, Cabora Bassa is at present (1983) 80% owned by Portugal and only 20% by Mozambique. At present (1983) South Africa takes most of the power produced by way of twin 1900 kilometres long transmission lines to the Apollo converting station near Pretoria.
Since announcing the north bank development, Mozambique has decided to reduce supplies to South Africa. A 2000 kilometre power line has been extended through Mocuba in the north as far as Nampula. It is now ready to power a new aluminium industry, iron and steel near Moatize, textile production, cashew nut factories, and the homes of Mozambique people themselves.
The dam has also brought agricultural benefits. Most of the whole region's rainfall comes between November and-April. The Zambezi flooded uncontrollably. During the other months there was often only a trickle of water along parts of its course. Soon, the Mpenda Uncua scheme which is 40 kilometres below Cabora Bassa and two other dams further downstream will ensure more power, flood control and reliable navigation facilities as far upstream as Tete.
Agricultural losses from flooding have been reduced and irrigation supplies new cotton, sugar and rice developments. Piped water will supply cattle and afforestation projects near Malawi,
Minerals should soon be exploited. The coal mines at Moatize can be expanded, there are iron ore reserves capable of yielding 1 million tonnes a year and perhaps the bauxite on Mount Mianje in Malawi can be exploited. The 170 square kilometres man-made lake will provide the basis for a fishing industry which could supply the region with its needs for protein.
No project of this size is without its problems. The land to be flooded by the lake had 25000 people living on it. They had to be resettled and this has been done around Moatize and Zobue, on land which will come under irrigation.
Cabora Bassa was a political dam, built by the South Africans and Portuguese to perpetuate their nold on the region. The Cunene Dam and Oxbow have similar aims. The money that migrant workers send home from South Africa, forming a major part of the income for Mozambique and Malawi, also had this aim. South Africa hopes that by weaving a vast interdependent economic web amongst her neighbours they will hesitate to shatter its stability and obvious benefits, by trying to overthrow her political system. Only time will produce the answer.